Proper usage: MRC and Metalica
eap at gloworm.Stanford.EDU
Sat Feb 24 01:33:21 PST 2007
MRC and metalica are not meant to be used the way some people
have been using them.
As someone who has been helping to routinely clean these systems for a
long time, I've noticed that there are many 10's of micron worth of
deposited material on both lately in a short time. (Etch crud on MRC, and
sputtered metal on metalica.) These systems were not designed
for making paperweights; they are THIN film systems designed
for small quantities of wafers. If you find yourself
depositing/sputter etching microns of film, you should rethink
your process. There's probably a better way.
We once had guidelines for what was considered appropriate,
but they seem to have faded. Since SNF doesn't run process
any longer, it's we, the users, who suffer from such misuse.
If everyone agrees that your process is worthy of such wear-and-tear,
then you should arrange with maintenance to properly clean up the mess
after you're through. Or you can contract to a production facility
with a production sputterer to meet your needs.
A related problem: when the crud builds up, some people have taken the
initiative to remove the crud by scrubbing deposition from the viewports
and chambers. You may clean dishes at home this way, but it's not the
proper method for cleaning a semiconductor chamber! This causes billions
of particles (remember, we still call this a CLEANroom, with all the white
suits, and particle filters in the ceiling),
and it damages parts of the machine- Particles become trapped in
valves, causing them to fail. Seals get impregnated with particles, and
start to leak. Moving parts grind abrasively.
A very light IPA wipe is sometimes appropriate (ask first!), but what I've
seen is hard scrubbing to abrade deposition away.
In short, if you weren't TAUGHT to do this (or other
procedures), DON'T DO it. There are even stickers saying not to do
it, but some lab members apparently can't read. Please take care of
the equipment as you would your own car. (I'd be happy to sandpaper
your windshield if you want visual clarification :^)
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